It should be about the same. If anything, loose ring might need to go up a 1/4 inch to avoid pinching. I have my WB in a 5.5 NeuSchule and bought the 5.5" loose ring for her and find it a little too small.

What I have now is a loose ring with French link. It's a 5 and the tag also says 16 mm. I'm guessing that's the thickness.

She is oh so fussy and mouthy always chomping on it. I would prefer not to have to tighten the flash to keep her from chomping.

My other struggle is to get her to relax and stay connected. I'm sure part of it is her breeding (andalusian) she just wants to take over and go. I am green and she is also greenish. I have to really take a lot on the reins to get her to give to the bridle and I hate having to take so much to get her to relax and give.

I was thinking your double jointed egg butt might be a good choice. When I have to get a hard hold on her I would think the egg butt would avoid any possible pinching. But since I don't have experienced hands I also don't want something that when I do have to take and hold with a strong fist that I do not cause tongue or palate pain.

Since you have used both your single and double jointed, which do you think would be easier on her mouth while still keep her from taking over and to accept and relax to the bit?

Well, IMO, a fussy mouth might do better with a single-jointed bit or even a mullen. When I bought Annabelle, she was 4 and going in a mullen-mouth western curb bit (at least not riding on contact...). The seller swore that she was quietest with her mouth in that bit, so I ended up putting her in a Myler level 1 snaffle, because it doesn't collapse and is somewhat thinner, making it similar to the bit she was used to. However, after riding in that for several months, it was helpful to use the single-jointed NovoContact for a few months to encourage her to reach for contact. The center of the bit is flattened and lays on the tongue to distribute pressure more broadly. After a while, she started to lean on the single-jointed, so I tried the double-jointed version because according to Herm Sprenger, it could help with leaning. However, it was NOT the bit for her, and I only used it about 5 times. Now she goes in a simple Korsteel single-jointed curved mouth eggbutt snaffle, and it seems like the right solution (for now).

I remembered that I had a set of the Rein-Aids "somewhere", LOL. Found them last nite, going to try them today. Will give her a few rides to see if they make a difference. When I rode last nite, she wasn't as mouthy as usual, but my trainer had a ride on her earlier in the day so I think he tuned her up a bit. If not, I'll do some research on the Mullen and also your single jointed eggbutt.